Investigations will be directed at elucidating the biochemical nature of cell-cell interactions that influence development and differentiation in the central nervous system. Reaggregate and surface cultures of neonatal mouse cerebellum will be used to monitor biochemical and morphological development. The role of cell surface components in histogenesis and subsequent biochemical developmental events will be assessed using rabbit antisera or mouse hybridoma immunoglobulins directed against specific cell surface molecules. The possible role of plasminogen activator or other protease in neural cell migration will be examined.